gcc/targhooks.c

   1 /* Default target hook functions.
   2    Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, USA.  */
  20
  21 /* The migration of target macros to target hooks works as follows:
  22
  23    1. Create a target hook that uses the existing target macros to
  24       implement the same functionality.
  25
  26    2. Convert all the MI files to use the hook instead of the macro.
  27
  28    3. Repeat for a majority of the remaining target macros.  This will
  29       take some time.
  30
  31    4. Tell target maintainers to start migrating.
  32
  33    5. Eventually convert the backends to override the hook instead of
  34       defining the macros.  This will take some time too.
  35
  36    6. TBD when, poison the macros.  Unmigrated targets will break at
  37       this point.
  38
  39    Note that we expect steps 1-3 to be done by the people that
  40    understand what the MI does with each macro, and step 5 to be done
  41    by the target maintainers for their respective targets.
  42
  43    Note that steps 1 and 2 don't have to be done together, but no
  44    target can override the new hook until step 2 is complete for it.
  45
  46    Once the macros are poisoned, we will revert to the old migration
  47    rules - migrate the macro, callers, and targets all at once.  This
  48    comment can thus be removed at that point.  */
  49
  50 #include "config.h"
  51 #include "system.h"
  52 #include "coretypes.h"
  53 #include "tm.h"
  54 #include "machmode.h"
  55 #include "rtl.h"
  56 #include "tree.h"
  57 #include "expr.h"
  58 #include "output.h"
  59 #include "toplev.h"
  60 #include "function.h"
  61 #include "target.h"
  62 #include "tm_p.h"
  63 #include "target-def.h"
  64
  65
  66 void
  67 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  68 {
  69 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  70   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  71 #endif
  72 }
  73
  74 enum machine_mode
  75 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  76 {
  77   if (m1 == m2)
  78     return m1;
  79   return VOIDmode;
  80 }
  81
  82 bool
  83 default_return_in_memory (tree type,
  84                           tree fntype ATTRIBUTE_UNUSED)
  85 {
  86 #ifndef RETURN_IN_MEMORY
  87   return (TYPE_MODE (type) == BLKmode);
  88 #else
  89   return RETURN_IN_MEMORY (type);
  90 #endif
  91 }
  92
  93 rtx
  94 default_expand_builtin_saveregs (void)
  95 {
  96   error ("__builtin_saveregs not supported by this target");
  97   return const0_rtx;
  98 }
  99
 100 void
 101 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 102                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 103                                 tree type ATTRIBUTE_UNUSED,
 104                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 105                                 int second_time ATTRIBUTE_UNUSED)
 106 {
 107 }
 108
 109 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 110
 111 rtx
 112 default_builtin_setjmp_frame_value (void)
 113 {
 114   return virtual_stack_vars_rtx;
 115 }
 116
 117 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 118
 119 bool
 120 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 121 {
 122   return false;
 123 }
 124
 125 bool
 126 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 127 {
 128   return (targetm.calls.setup_incoming_varargs
 129           != default_setup_incoming_varargs);
 130 }
 131
 132 enum machine_mode
 133 default_eh_return_filter_mode (void)
 134 {
 135   return word_mode;
 136 }
 137
 138 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 139
 140 unsigned HOST_WIDE_INT
 141 default_shift_truncation_mask (enum machine_mode mode)
 142 {
 143   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 144 }
 145
 146 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 147
 148 bool
 149 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 150 {
 151   return true;
 152 }
 153
 154
 155 /* The generic C++ ABI specifies this is a 64-bit value.  */
 156 tree
 157 default_cxx_guard_type (void)
 158 {
 159   return long_long_integer_type_node;
 160 }
 161
 162
 163 /* Returns the size of the cookie to use when allocating an array
 164    whose elements have the indicated TYPE.  Assumes that it is already
 165    known that a cookie is needed.  */
 166
 167 tree
 168 default_cxx_get_cookie_size (tree type)
 169 {
 170   tree cookie_size;
 171
 172   /* We need to allocate an additional max (sizeof (size_t), alignof
 173      (true_type)) bytes.  */
 174   tree sizetype_size;
 175   tree type_align;
 176
 177   sizetype_size = size_in_bytes (sizetype);
 178   type_align = size_int (TYPE_ALIGN_UNIT (type));
 179   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 180     cookie_size = sizetype_size;
 181   else
 182     cookie_size = type_align;
 183
 184   return cookie_size;
 185 }
 186
 187 /* Return true if a parameter must be passed by reference.  This version
 188    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 189
 190 bool
 191 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 192         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 193         bool named_arg ATTRIBUTE_UNUSED)
 194 {
 195   return targetm.calls.must_pass_in_stack (mode, type);
 196 }
 197
 198 /* Return true if a parameter follows callee copies conventions.  This
 199    version of the hook is true for all named arguments.  */
 200
 201 bool
 202 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 203                           enum machine_mode mode ATTRIBUTE_UNUSED,
 204                           tree type ATTRIBUTE_UNUSED, bool named)
 205 {
 206   return named;
 207 }
 208
 209 /* Emit any directives required to unwind this instruction.  */
 210
 211 void
 212 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 213                      rtx insn ATTRIBUTE_UNUSED)
 214 {
 215   /* Should never happen.  */
 216   gcc_unreachable ();
 217 }
 218
 219 /* True if MODE is valid for the target.  By "valid", we mean able to
 220    be manipulated in non-trivial ways.  In particular, this means all
 221    the arithmetic is supported.
 222
 223    By default we guess this means that any C type is supported.  If
 224    we can't map the mode back to a type that would be available in C,
 225    then reject it.  Special case, here, is the double-word arithmetic
 226    supported by optabs.c.  */
 227
 228 bool
 229 default_scalar_mode_supported_p (enum machine_mode mode)
 230 {
 231   int precision = GET_MODE_PRECISION (mode);
 232
 233   switch (GET_MODE_CLASS (mode))
 234     {
 235     case MODE_PARTIAL_INT:
 236     case MODE_INT:
 237       if (precision == CHAR_TYPE_SIZE)
 238         return true;
 239       if (precision == SHORT_TYPE_SIZE)
 240         return true;
 241       if (precision == INT_TYPE_SIZE)
 242         return true;
 243       if (precision == LONG_TYPE_SIZE)
 244         return true;
 245       if (precision == LONG_LONG_TYPE_SIZE)
 246         return true;
 247       if (precision == 2 * BITS_PER_WORD)
 248         return true;
 249       return false;
 250
 251     case MODE_FLOAT:
 252       if (precision == FLOAT_TYPE_SIZE)
 253         return true;
 254       if (precision == DOUBLE_TYPE_SIZE)
 255         return true;
 256       if (precision == LONG_DOUBLE_TYPE_SIZE)
 257         return true;
 258       return false;
 259
 260     default:
 261       gcc_unreachable ();
 262     }
 263 }
 264
 265 bool
 266 default_vect_misaligned_mem_ok (enum machine_mode mode ATTRIBUTE_UNUSED)
 267 {
 268   return !STRICT_ALIGNMENT;
 269 }
 270
 271 bool
 272 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 273         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 274         enum machine_mode mode ATTRIBUTE_UNUSED,
 275         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 276 {
 277   return false;
 278 }
 279
 280 bool
 281 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 282         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 283         enum machine_mode mode ATTRIBUTE_UNUSED,
 284         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 285 {
 286   return true;
 287 }